Wooden slab for building purposes



Sept. 20, 1949. u. l.` s. l-:DLUND l 2,482,405

WOODEN SLAB FOR BUILDING PURPOSES Filed Jan. 6, 1947 E g4. MM5@ @JMWPatented Sept. 20, 1949 2,482,405 WOODEN SLAB FOR BUILDING PURPOSES UnoIvan Samuel Edlund, Akers Styckebruk, Y

Sweden Application January 6, 1947, Serial No. 720,377

In Sweden Sep 2 Claims.

The present invention relates to the manufacture of reinforced woodenelements, or slabs, of flat shape especially for use in setting upmoulds for concrete constructions.

Said elements according to the invention are built of pieces of boardwith their longer edges abutting against each other, said pieces ofboard being connected together, in part, by means of corrugatedfasteners arranged so as to cross the joints substantially under rightangles and, in part, by means of metallic bars engaging grooves formedin the ends of the connected boards which are sealed in this engagementby means of appropriate cramp-irons or the like. Said corrugatedfasteners permit expansion of the boards owing to moisture and effectcontractions thereof when the boards again become dry. The rods or barsengaging the grooves at the ends of the boards tend to maintain theboards of an element in the same plane, so as to prevent the element asa whole from warping Ywhile at same time armouring and stiiening it. f

In the accompanying drawing an embodiment of the invention is shown byway of example.

Fig. 1 is a plan view of a slab constructed in accordance with thisinvention. Fig. 2 is a side view as seen in the direction of line II-IIof Fig. 1. Fig. 31s an end View. Figs. 4 and 5 are detail views on alarger scale showing a corrugated fastener as seen from its edge and inplan View, respectively.

A wooden element, or slab, according to this invention is built up of anumber of pieces of board l, with their longer edges abutting againsteach other or engaging each other by means of tongues and grooves.

To hold the pieces of board together corrugated fasteners 2 areutilized, which are driven into the pieces of board so as to cross thejoints therebetween, substantially at right angles. Such fasteners maybe used either on one surface of the slab only or on both surfacesthereof. In the said last-mentioned case the fasteners on one surface inthe direction of the joints with relation to those on the other surface,as will appear from Fig. 2. In Figs. 4 and 5 a separate fastener isillustrated. Y

The fastening elements due to their corrugated Vshape allow expansionsof the slab under the iniluence of moisture and act to draw the piecesof boards together when dried so as to avoid gaps between the individualpieces of board.

To hold the slab flat under all conditions and guide them under the saidexpansions and contember 21, 1943 it is preferred to displace ytractions rods or bars 3 are used, let into grooves formed at the endsof the slab, each groove receiving a rod or bar that extendssubstantially over the entire width of the slab. To seal the rods orbars in the grooves cramp-irons 4 are used, which are driven into thepieces of board. At one end each rod or bar is sharpened to a point andbent so as to form a nail 5 that may be driven into the wood of therespective board. The rods or bars 3 act to maintain the boards of anelement, or slab, in at state, thereby stifening it and keeping it fromwarping.

What I claim is:

1. A wooden element for use in setting up moulds for concreteconstructions, comprising in combination, a set of pieces of boardsplaced with their longer `edges abutting each other, so as to form aplane slab, said slab having grooves in Opposite ends thereof thegrooves at the respective ends being in alignment with each other,corrugated elastic metal fasteners driven into adjacent pieces of boardsacross the joints therebetween for keeping each two pieces of boardstogether while allowing expansion thereof under the influence ofmoisture and for positively drawing them close to each other when theybecome dry and contract, each such fastener to this end being of alength -considerably shorter than the width of a piece of board, andmetallic bars in said grooves, means for securing said bars againstdislodgment from the grooves, said bars providing a flat state of theslab under variable conditions.

2. Anelement as claimed in claim 1, and in which one end of eachmetallic bar is formed with a bent pointed end for acting as a nail inensagement with the material of the slab.

UNO IVAN SAMUEL EDLUND.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 666,345 Goehst Jan. 22, 19012,143,764 DeWitt Jan. 10, 1939 2,276,170 Elmendorf Mar. 10, 1942 FOREIGNPATENTS 5 Number Country Date 21,343 Great Britain Oct. 11, 1898 4,947Great Britain Mar. 1, 1907 115,433 Sweden Nov. 27, 1945

